Sizing cellulosic and acrylic staple fiber yarns with acrylonitrile/acrylic acid copolymer



United States Patent 3,519,477 SIZING CELLULOSIC AND ACRYLIC STAPLEFIBER YARNS WITH ACRYLONITRILE/ ACRYLIC ACID COPOLYMER Hans Wolf,Ludwigshafen (Rhine), Herbert Spoor, Mutterstadt, Pfalz, and WilhelmRuemens and Heinz Pohlemann, Limburgerhof, Pfalz, Germany, assignors toBadische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine),Germany No Drawing. Filed Jan. 31, 1967, Ser. No. 612,811 Claimspriority, application Germany, Feb. 1, 1966, 1,594,905 Int. Cl. D02g3/40; B32b 27/08, 27/12 US. Cl. 117-1395 8 Claims ABSTRACT OF THEDISCLOSURE Sizing materials for stable yarns consisting of, orcontaining, a water-soluble polymer which contains copolymerized unitsof (a) acrylonitrile and (b) acrylic I acid and its sodium or ammoniumsalt in the molar ratio of (a):(b)=l:l.5 to 1:7.

In the textile industry it is customary to treat yarns, especially warpyarns containing cotton or staple yarns containing other cellusoicfibers, with hot, that is, almost boiling, aqueous preparations of corn(maize) or potato starch prior to weaving. This pretreatment of theyarns, known in the trade as sizing, serves to secure cohesion of thespun fibers and to improve their mechanical strength so that they canstand up better to the stresses arising during the weaving process thanthey would in the raw and untreated state. In addition to naturalvegetable starches, chemically modified starch products are employed forsizing cotton, these being easier to remove than normal starches andproducing liquors of comparatively low viscosity. Lubricants, such astallow, are frequently added to sizing liquors containing mainlystarches. The fatty substance is added to improve the slip of thethreads and to prevent them becoming too brittle. Usually, the sizingagent has to be removed from the woven material prior to furthertreatment, and this is achieved to a more or less satisfactory extentonly by subjecting it to the action of enzymes for several hours.

In some cases, cotton or other cellusoic yarns are sized with substancesthat have been produced by the chemical modification of cellulose. Suchsubstances include cellulose ethers, for example carboxymethylcelluloseor methylcellulose. These are commonly marketed in the form of powderswhich can be made up as collodial aqueous solutions only by prolongedstanding in water, by vigorous stirring or kneading, or by heating. Ingeneral, their solutions are not homogeneous, but turbid andcomparatively highly viscous. Frequently, the powders, owing on thechemical modification of the cellulose, contain large quantites ofcommon salt. It is well known, however, that common salt is the sizingliquor readily causes corrosion of the weaving equipment; Evencarboxymethylcellulose type products usually have to be applied to theyarns from a hot liquor, and this not only requires a considerableamount of steam, but also impairs the yarn to some extent, for instance,by causing a reduction in extensibility. Sizing with cellulose ethersproduces only comparatively Weak sizing efiects on cellulosic yarns, sothat improvement in the mechanical propreties of the yarn is onlyslight, and the effect of such sizes is to produce a yarn that is toosoft.

Attempts have already been made to employ synthetic polymers as sizingagents for staple yarns of cellulosic fibers or acrylic fibers, or yarnscontaining these. Thusv 3,519,477 Patented July 7, 1970 in US. Pat.2,819,189 it is proposed to size continuous filament of staple yarns ofa great variety of types by employing copolymers which contain carboxyland nitrile groups in a molar ratio of 0.3:1 to 0.75:1 either free orcombined with sodium potassium or ammonium in a 5 percent aqueoussolution at 60 C. at a pH value of between 5 and 9 and with a viscosityof between 5 and 200 cp. However these synthetic sizing agents stillleave much to be desired. The sizing efiects attainable are not alwaysadequate, and it is expressly emphasized in US. Pat. 2,819,189 that itis important to remain within the molar ratios indicated in order toobtain good results. This is denoted as being particularly importantbecause the sizing action of the polymers falls olf markedly even nearthe limits of the molar ratios defined in the specification. A furthersignificant disadvantage of these essentially neutral polymers is thefact that they are only partially soluble in water. Some of thesepolymers, particularly those with a high nitrile content, are onlycollodially soluble, or even entirely insoluble, in water and these aretherefore supplied as aqueous dispersions. Such dispersions aresometimes so unstable that they often coagulate even as they aremanufactured, so that they become unusable. Sizing agents of this type,that are not completely soluble in Water, are not readily scoured offthe fabric.

It is an object of the present invention to provide sizing agents forstaple yarns which consist of or contain at least 30 percent by weightof cellulose and/or acrylic fibers and which are more effective than thesizing agents hitherto employed for such yarns.

Another object of the invention is to provide sizing agents for the typeof yarns mentioned which are particularly readily soluble in Water.

Still another object of the invention is to provide sizing agents forthe type of fibers mentioned which are chemically and mechanically verystable in the treatment liquors.

A further object of this invention is to provide sizing agents for thetype of yarns mentioned which can be removed from the yarns particularlyeasily.

A still further object of the invention is to provide an improvedprocess for sizing the type of yarns mentioned which, compared withprocesses employed hitherto, effects savings in energy and personnelcosts and an increase in productivity when processing the sized yarns,and which also ensures more satisfactory and easier desizing.

Other objects will be apparent from the following detailed description.

These objects are achieved by the present invention which is based onthe surprising discovery that polymers which are of a very similarcomposition to those in US. Pat. 2,819,189 produce markedly superiorresults, not only as regards water solubility, but also with respect totheir sizing effects, when the componentsof the polymers are used indifferent molar ratios and the polymers are applied in acidic form.

It has been found that staple yarns consisting of or containingcellulosic fibers and/or acrylic fibers in an amount of at least 30'percent by weight can be sized better than hitherto by applying to theyarn an aqueous solution of a polymer containing copolymerized units of(a) acrylonitrile and (b) acrylic acid and its sodium or ammonium saltin the molar ratio of (a) (b) of 1:15 to 1:7, preferably from 1:2 to1:6, its 10 percent by Weight aqueous solution at 20 C. having aviscosity of 20 to 2000 cp. and a pH value of 2.5 to 6.5, preferably 3to 5.5, and drying the yarn thus treated.

Staple yarns that can be sized according to the invention include, forexample, those of natural and/or regenerated cellulose such as cotton,rayon staple, linen and their blends with one another and with otherstaple fibers such as polyester and acrylic fibers and their blends withother staple fibers. Our acrylic fibers are understood both fibersprepared from acrylonitrile homopolymers and those of copolymers ofacrylonitrile with up to approximately 20 percent by weight of othermonomers, e.g., methyl acrylate, vinyl acetate and vinyl pyridine.

The polymers used in the form of their solutions in accordance with theinvention can, in addition to the monomers described under (a) and -(b)above, incorporate up to 20 percent by weight of coplymerized units ofother, at least partially water-soluble, monomers, such as acrylamide,methacrylamide, methyl acrylate, methacrylic acid or its alkali orammonium salts, maleic acid or its salts or semiesters,methacrylonitrile and vinyl pyrrolidone. They can be prepared byconventional processes, preferably by the copolymerization of acrylicacid with acrylonitrile and, if desired, other monomers in aqueoussolution, and by subsequent partial neutralization of the carboxylgroups contained in the polymers by means of an alkali or ammoniumhydroxide to set up the molar ratio between the free acrylic acid groupsand the sodium or ammonium carboxylate groups which produces therequired pH value of the polymer solution. A further method ofpreparation consists in copolymerizing mixtures which already containacrylic acid, sodium or ammonium acrylate and acrylonitrile in thedesired molar proportions. In general, the polymers to be used inaccordance with the invention contain carboxylic acid groups and sodiumor ammonium carboxylate groups in the molar ratio of approximately 1:03to 1:3, preferably from 1:0.8 to 1:2. The polymers can be applied assizing agents either in the form obtained in manufacture or afterdilution. However, they can also be dried to a powder and dissolved inwater before use.

As a 10 percent aqueous solution at 20 C. the polymers should have aviscosity of from 20 to 2000 cp., polymers having a viscosity of from250 to 2000 cp. under the said conditions being preferred. The viscosityis expediently determined with a Hoppler falling sphere viscometeraccording to German standard specification DIN 53,015.

The solutions employed in accordance with the invention preferablycontain 0.5 to 20 percent by weight of polymer. The followingconcentrations have proved particularly satisfactory: 0.5 to for rayonstaple and linen, 3 to for cotton, and 5 to percent by weight foracrylic staple fiber. The size solutions have pH values ranging fromapproximately 2.5 to 6.5, preferably from approximately 3 to 5.5,depending on the molar ratio of free carboxylic acid groups to sodium orammonium carboxylate groups present in the polymer.

In addition to the polymers mentioned, the solutions according to theinvention can contain conventional sizing agents and/or sizingauxiliaries, e.g., chemically moditied starches, carboxymethylcellulose,methylcellulose, polyvinyl alcohol and emulsified fats; such additives,however, should not constitute more than 50 percent by weight of thesolids content of the sizing liquors, and preferably not more thanpercent by weight.

The polymer solution employed for sizing in accordance with theinvention can be brought on to the yarn at temperatures of between 0 and100 C. In many cases, however, it is particularly advantageous to employthe liquor at a temperature of between 10 and C., that is, atapproximately room temperature. Nevertheless, the polymer solution canalso be used at higher temperatures, in which case the associated fallin viscosity permits working at a higher concentration resulting in aconsiderable increase in the output of the sizing machine since lesswater has to be evaporated from more concentrated solutions on drying.

The application of the size to the yarn is carried out in the usualmanner, that is, mainly on machines well known in the open width sizingof warps. However, it may also be applied to the individual yarn, forinstance, on a cross-Wound package. It is also possible to apply thesize to bobbins or warp beams by means of appropriate dyeing machinery.It is preferable to apply the sizing agent in such an amount that thetreated yarn carries 0.5 to 10 percent of polymer, referred to theweight of the untreated, dry yarn.

The present invention possesses a number of important technicaladvantages:

The polymers of the invention are particularly readily soluble in water.A consequence of this is that the sizing liquors can be prepared withcold water and require only moderate stirring, particularly when thepolymer is in the form of an aqueous solution. In the process of theinvention, the use of pressure boilers and steam or other thermal energyfor preparing the sizing liquors, such as is necessary with most of theexisting sizing agents and especially with starch products, can bedispensed with. Labor costs can be saved as a result of the considerablysimpler and more rapid preparation of the liquor, and the danger ofpersonnel being scalded is reduced.

No evaporation losses occur during application at normal temperature, anit is particularly easy to keep the temperature and concentration of thesizing baths constant. Furthermore, it must be pointed out that thepolymers of the invention produce sizing effects equivalent or evensuperior to those of conventional sizes, even at considerably lowerrates of application.

The fact that smaller amounts of sizing agent are required also meansthat more yarn can be wound onto a warp beam than is the case withconventional sizing agents, so that weaving capacity is increased andsavings are effected in ancillary machinery.

Another important advantage is the stability of the sizing liquors whichcan, if necessary, be stored for weeks without undergoing change. Sizingliquors based on starch, on the other hand, lose considerably inefficiency even on storing for only a few hours, so that they have to bediscarded in the evening or at the end of the week. Thus, compared withprior processes, the new process offers the possibility of savings inthe cost of materials. A considerable reduction in the number of brokenends on the loom can be achieved as a result of the invention. This alsomeans that the productivity of the loom is increased. Warps sized inaccordance with the invention does considerably less than warps sized byconventional processes.

Yarns sized in accordance with the invention are more resistant toabrasion than yarns treated with starch products, cellulose ethers, orin accordance with the invention described in U.S. Pat. 2,819,189.Furthermore, the yarns can be desized more easily, since simple scouringor rinsing is all that is required. Faulty dyeings and difiiculties infinishing, so very often attributable to inadequate desizing, arelargely elminated by the process of the invention.

From the point of view of river pollution the low biochemical oxygendemand for the sizing agents of the invention is particularlyadvantageous as compared with that of the most commonly used starchsizes. The high biochemical oxygen demand of saccharification productsof starch often leads to a considerable disturbance of the biologicalequilibrium in the rivers into which the effluents run, and may resultin anaerobic fermentation and odor nuisance. The superiority of thepolymers of the invention over those described in U.S. Pat. 2,819,189can be seen principally in the fact that, as homogeneous solutions, theyare much easier to use than dispersions which are very unstable in somecases. Whereas such dispersions and colloidal solutions exhibit a markedtendency to tures or subjected to repeated freezing and thawing. It iswell known that good transport and storage stability is of importance inpractice. The invention is further illustrated by, but not limited to,the following examples in which the parts and percentages specified areby weight.

Testing of the yarns was carried out under standard conditions, namely,at 20 C. and 65 percent relative humidity. The mechanical values givenin the stables constitute the mean values of or individualdeterminations, as the case may be. The abrasion number is the averagenumber of abrasions up to breakage of the yarn, and has been measured onthe apparatus described by E. Kenk in Textil-Praxis, 7, 9, 6 98 (1952).

EXAMPLE 1 A cotton yarn, of Nm. 34/ 1 count, was treated with twodifferent sizing liquors on a laboratory sizing machine consisting ofone pair of squeeze rollers with a sizing trough capable of beingheated, a drying tube heated with hot air, and a wind-on deviceoperating at constant tension; the conditions were otherwise identicalin both cases.

Liquor 1(a) Parts Potato starch 77 Degraded starch 16 Bone glue 6Emulsified fat 1 4 the liquor being made up to 900 parts with water.

This mixture, which has a formulation well tried in practice, was boiledup for minutes and then applied at 85-90 C.

Liquor 1(b) This comprised a 15 percent aqueous solution of a polymerwhich was made up, on the one hand, with acrylic acid and sodiumacrylate and, on the other, acrylonitrile, the two groups of componentsbeing in the molar ratio of 2:1. When diluted to 10 percent, thesolution had a viscosity of 315 cp. at 20 C. and a pH value of 4.5. Theliquor contained no other additives and was applied at 20 C.

On comparing untreated Nm. 34/1 cotton yarn with the two yarns sized inliquors 1(a) and 1(b) respectively, after conditioning for 24 hours at20 C. and 65 percent relative humidity, the values presented in thefollowing table are obtained:

Coating Elongaweight Breaking tion at (weight Abrasion ad break percent)number (g.) (percent) Untreated 105 316 8. 4 Treated with liquor 1(a 19.8 1517 599 4. 3 Treated with liquor It can be seen from these figuresthat the cotton sized according to the invention with formulation 1(b)at room temperature has a greater extensibility, a larger abrasionnumber, and about the same breaking load as thattreated sizing machinedescribed in Example 1 with three different sizing liquors at a bathtemperature of 20 C. The composition andpreparation of the sizingliquors were as follows:

6 Liquor 2(a) 120 parts of a commercial carboxymethylcellulose powderrecommended for sizing cotton, and 880 parts water.

This size powder was slowly stirred into hot water at C., allowed toswell overnight, and then vigorously stirred once more on the followingday. In spite of this, the liquor was not homogeneous and entirelyclear, but turbid and with swollen particles distributed throughout it.

Liquor 2 (b) 400 parts of a 25 percent aqueous solution of a polymermade up of acrylic acid, ammonium acrylate and acrylonitrile in molarproportions of 1:0.8:0.5 (corresponding to a molar ratio of acrylate toacrylonitrile, (a):(b) =1:3.6), whose 10 percent solution at 20 C. has aviscosity of 635 cp. and a pH value of 4.3, were diluted with 600 partsof water by simple stirring.

The liquor 2(b) obtained in this manner is color less, clear, andhomogeneous.

Liquor 2(c) Coating Elongaweight Breaking tion at (weight Abrasion loadbrealr percent) number (g.) (percent) Untreated 206 5. 2 Treated withliquor 2 a 9. 2 234 4. 9 Treated with 1 nor 2(b 8. 9 486 289 4. 0Treated with liquor In spite of the low liquor concentration and inspite of the small amount applied, the superiority of the size appliedin accordance with formulation 2(b) of the invention is made evident bythe resultant higher breaking load and considerably higher number ofabrasion cycles required to effect rupture of the fiber.

EXAMPLE 3 Two 10,000 m. long warps containing 4,600 cotton threads (Nm.68/ 1) were sized for comparison purposes in different liquors on anopen-width sizing machine equipped with a cylinder dryer. Liquor 3(a)was prepared by submitting a suspension of 35 parts of potato starch and35 parts of a commercial esterified starch ether sizing agent in 430parts of water to boiling for about 40 minutes while stirring. Liquor3(b) was prepared by stirring parts of a 25 percent solution of apolymer of acrylic acid, ammonium acrylate and acrylonitrile in themolar proportions 1:1:0.6 (COIICSpOITCElg to the molar ratio of acrylateto acrylonitrile, (a):(b)=1:3.33) into 375 parts of water at roomtemperature. A 10 percent solution of this polymerhad a viscosity of 288cp. and a pH value of 4.5.

Whereas liquor 3(a) had to be applied to the warp at 85 to 90 C. inorderto prevent gelling of the starch paste, liquor 3(b) could be applied atroom temperature. Both warps were subsequently lubricated on the sizingmachine with a molten commercial grease.

The above two warps were then woven on similar looms and under the sameconditions. The warp sized with liquor 3(a) had an average of 47 brokenends per 100,000 picks, while the warp sized according to the inventionwith liquor 3(b) had an average of only 1.6 broken ends per 100,000picks. Each of these constitutes the mean values of observations madeover approximately 500,000 picks.

made from the (b) warp presented a very much more even appearance thanthat produced with the 5(a) warp.

EXAMPLE 6 Each of two warps containing 787 linen threads (Nm.

To remove the size from the loom-state cloth, the goods 5 f r wels wassized in one of two difl'erent sized with liquor 3(a) had to besubjected to a desizing l q n an pp machlue q pp W 1th a Y processlasting several hours in the presence of enzymatic l der dryer. L1quor6(a) compnsed a suspension of desizing agents, this being followed byopen-width scour- Parts Of a com crclal starch der1vat1ve and 1.5 partsof ing, whereas the goods sized with liquor 3(b) simply r 10 anemuls1fiable fat 1n 490 parts of water, whlch had been quired a coldcour to remove the size boiled up for 10 minutes WhllC being Slill'ffidand then applied at 60 C. EXAMPLE 4 Liquor 6(b) comprised a solution of5 parts of a lymer of acrylic acid ammonium acrylate and acrylo- A red-ded 800 m.1on acr l1c fiber war Nm. 40/1) a containing/3,600 ends ia};veaving f 120 n1tr1le 1n molar proportions of 1:1.5 :1 (correspondingto was sized with two different sizing liquors on an openi of(a):(b)=1:2'5) 2 parts of Water width machine equipped with an airdryer. Liquor 4(a) 1e r0021 e e 10 percent was prepared by boiling andstirring a suspension of 40 t g a vlseoslty of 1130 and a parts ofpotato starch and 25 parts of a chemically modi- P Va ue 0 fied starchwith 335 parts of water for 1 hour. Liquor ,T warps Slzed Wlth theorespeetlve hquors were 9 4(b) consisted of an 8 percent aqueoussolution of the P F for 24 hours at 20 65 percent relatlve polymerdescribed in Example 3. Liquor 4( a) was applied hemldlty whereupon theywere mvestlgated and eompared to the yam at c and liquor 4(b) at C another with untreated yarn. The values 1n the followlng table conditionsbeing identical. Investigation of the yarns in were obtamed: comparisonwith untreated yarn gave the values presented 25 in the fOllOWiHg table:Coating Elongaweight Breaking tion at (weight; Abrasion load breakCoating Elon percent) number (g.) (percent) h B k t" t $3511? Abrasion132 b'ie k gfiggg g m g 662 11732 percent) number (g.) cent) T g H t}; 10 1' 144 1 595 2 o a 1 I101 gg g 116 489 2 eliv 0. e 1, 554 1, 689 2. e

4(a) 12. 3 736 530 19. 2 T- t d t 1 nor f i) l.. 8 564 In spite of theconsiderably smaller amount of S126 applied, warp 6(b), which had beensized in accordance In assessing the weaving behavior of the two warpswith the invention with a cold liquor, behaved better on practically nodifference can be established without the WeaYmg than warp as shown bybetterfiheddmg, less statistical determination of the number of brokenends, dustlng, and fewer k n ends. An ther important adand this despitethe fact that the amount of sizing agent Vantage was the ease of Washlngout 5126 applied in accordance with the invention was not even 2311fEXAMPLE 7 as great as that applied by t e convent1ona process. e warpsized with formulation 4(b) in accordance with the .Stap 1e rayon(polynoslc 48/1) W i slzed invention was virtually non-dusting, whereasthe warp i the hquors on the laboratory 512mg sized with formulation 4(a) produced an extremely large 0 me descnbed m Example amount of dust.To this must be added the fact that the Liquor 7(a) loom-state clothsized with formulation 4(a) has to be This consi o sted of a hot (85 C.)aqueous preparation of i ig g fg i g gg gi gg 55 52 g i g g ggi g 30parts of carboxymethylcellulose, 30 parts sodium polyf0 methacrylatesolut1on (30 percent in water), 2 parts of open'wl or m rope mineral oilemulsion and 938 parts of water.

EXAMPLE 5 Liquor 7(b) The F liquors descfibed Example 4 were dilufedThis consisted of a hot (85 C.) aqueous preparation y One-fluid 0fVolume wlthhot Water (formula?!on of 30 parts of a polymer of acrylicacid, sodium acrylate and cold Water (formulatlon and 100 55 andacrylonitrile in the molar ratio of 1:2:0.6 (correlengths of a warpcontaining 2,400 pale blue rayon staple/ sponding to the molar ratio of(a) (b)=1;5; a 10 f 'yl fiber blend y z Slzfid cent aqueous solution ofthis polymer had a viscosity of 1H elfllel The Values p m 011lllvestlgatlng the 1880 cp. and a pH value of 5.3), 10 parts of acommercial two f P In COmPaHSOII Wlth untreated Y are p water-solublestarch ether and 940 parts of water. Sentfid In the followlng table? Thefollowing data were obtained on testing the fibers:

6 ti El wogigrlllf r ing tioei e t @3 11? Breaking gii a t (weightAbrasion 108 break (weight Abrasion load break percent) numb er (g.)(percent) 6 5 percent) numb (percent) --1 257 279 1 Untreated T 83 34811. 4 233 i 11. 5 686 294 10.2 r l wlthhqum 7 3 374 345 6 3 Treated'w'itli use; Tre ted with lidiffz to be expficted from these Valli-{65,p The warp sized with liquor 7(b) in accordance with sized With the 5(b)11ql10r 1n accorda ce with t e ln the invention had better weavingcharacteristics than that tion behaved similarly on the loom to the warptreated of 7(a) because of its very high abrasion rating obtained withthe 5(a) liquor. The 5(b) warp, however, produced in spite of theconsiderably smaller amount of sizing agent very much less dust than the5(a) warp, and the material applied.

9 EXAMPLE 8 A polyester fiber/cotton blend (67/33) yarn (Nm. 69/1) wassized with two different liquors on the lab oratory sizing machinedescribed in Example 1. Liquor 8(a) was obtained by boiling up asuspension of 230 parts of a commercial starch derivative and 16 partsof a commercial emulsified fat in 850 parts of water until the viscositybecame approximately constant, this taking about 45 minutes. Thisliquor, which is representative of a commercially employed formulation,was applied at 90 C.

Liquor 8(b) was obtained by stirring 300 parts of an aqueous 30 percentsolution of a copolymer of acrylic acid, sodium acrylate andacrylonitrile in the molar ratio of 1:2:1 (corresponding to the molarratio of (a) :(b): 1:3) into 700 parts of water at room temperature; apercent solution of the polymer had a viscosity of 420 cp. and a pHvalue of 5.2. The liquor was applied to the yarn at room temperature.

Investigation of these two sized yarns and untreated yarn gave thefollowing values which demonstrate the superiority of sizing liquor 8(b)prepared and applied in accordance with the invention.

Coating Elongaweight Breaking tion at (weight Abrasion load breakpercent) number (g.) (percent) Untreated 195 279 13. 1 Treated withliquor 8(a 22. 7 502 286 9. 6 Treated with liquor monium salt in themolar ratio of (a) (b) of from 1:15 to 127, a 10 percent by weightaqueous solution of said polymer at 20 C. having a viscosity of 20 to2000 cp. and a pH value of 2.5 to 6.5, in order to deposit on said yarnat least about 0.5% by weight of said polymer with reference to theweight of the untreated dry yarn; and drying the yarn thus treated.

2. A process as claimed in claim 1, in which the poly mer is applied inan amount of 0.5 to 10 percent, referred to the weight of the untreateddry yarn.

3. A process as claimed in claim 1, in which the molar ratio of (a):(b)in the polymer is from 1:2 to 1:6.

4. A process as claimed in claim 1, in which a 10 percent by Weightaqueous solution of the polymer at 20 C. has a viscosity of 250 to 2000cp.

5. A process as claimed in claim 1, in which a 10 percent by Weightaqueous solution of the polymer at 20 C. has a pH value of 3 to 5.5.

6. A process as claimed in claim 1, in which an aqueous solutioncontaining 0.5 to 20 percent by weight of polymer is applied to theyarn.

7. A process as claimed in claim 1, in which the aqueous solution of thepolymer is applied to the yarn at a temperature of between 10 and 30 C.

8. A process as claimed in claim 1, in which the poly mer containscarboxylic acid groups and sodium or ammonium carboxylate groups in themolar ratio of from 1:0.8 to 1:2.

References Cited UNITED STATES PATENTS 2,819,189 1/1958 Suen et a1.117139.5

WILLIAM D. MARTIN, Primary Examiner T. G. DAVIS, Assistant Examiner US.Cl. X.R.

ll7l38.8, 161, 143,

